Automatic paper feeder



United States Patent Inventors Alex M. Muller Redondo Beach, California;Kunio A. Sumida, Los Angeles, Calif. Appl. No. 744,583 Filed July12,1968 Patented Dec. 8, 1970 Assignee Telautograph Corporation LosAngeles, California a corporation of California AUTOMATIC PAPER FEEDER 9Claims, 5 Drawing Figs.

US. Cl 271/10, 271/57 Int. Cl B65h 5/06, B65h 7/18 Field ofSearch271/10, 36,

[56] References Cited UNITED STATES PATENTS 2,759,729 8/1956Hedlun............;......... 271/10 3,339,917 9/1967 Petrovsky 271/36Primary Examiner Edward A. Sroka Attorney Lindenberg & F reilichABSTRACT: Apparatus for feeding individual sheets of paper from a stackthrough a facsimile transmitter with a minimum spacing betweensucceeding sheets. The apparatus comprises a feed roller which rapidlymoves a sheet from the stack along a feed path to a slow moving belt,and a paper sensing switch which stops rotation of the feed roller assoon as the leading i edge of the sheet reaches the belt. When thetrailing edge of the sheet leaves the position of the paper sensingswitch, the feed roller is again driven to remove another sheet and sendit rapidly to the belt.

AUTOMATIC PAPER-FEEDER BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to paper feeding mechanisms.

2. Description of the Prior Art One type of facsimile transmitteraccepts a stack of paper with images thereon and feeds the sheets ofpaper one at a time into a scanner. The scanner scans the sheet, oneline at a time, and transmits the images to a distant receiver. In orderto provide reliable automatic operation, the paper feeder must deliveronly one sheet at a time, leaving at least a small gap betweensucceeding sheetsJForefticient utilization of the apparatus, the gapbetween sheets must be very small.

One prior art feed apparatus utilizes a feed roller which moves onesheet at a time from a'stack holder to a belt. The belt engages thesheet and carries it at a slowspeed, such as 6 inches perminute, past anoptical scanner. The feed roller turns continuously to remove one sheetafter another from the stack. However, the roller turns at a-slightlyslower speed than the belt in order to leave a small gap between thetrailing edge of one sheet and the leading edge of the next sheet. Thefeed rollers become worn and may slip on the paper so that a large gapis left between sheets. This results in the user paying for the hightransmission costs while no image is being transmitted. In addition, thefeed rollers often skew the paper, and following sheets tend to acquirethe same skew so that information on edge portions of the sheet may notbe transmitted.

OBJECTS AND SUMMARY OF THE INVENTION One object of the present inventionis to provide a slow rate feeding mechanism which.limits skew and whichassures a small but controlled gap between successive sheets.

Another object is to provide apparatus for the more positive control ofpaper feeding] i In accordance with the present invention, a mechanismis provided for positive control of paper feeding, to reduce skew and toreduce the gap between succeeding'sheets of paper. Such feed mechanismsfind particular use in a facsimile transmitter wherein the paper ismoved slowly past a scanner. The sheet feeding mechanism comprises aslow sheet transport for final handling of thesheet and a fast sheettransport for moving individual sheets from a stack to the slow sheettransport. A sheet sensing switch is located near the point where sheetsare transferred from the fast transport to the slow transport.

point of transfer betweenthe fast and slow transports, means areprovided for abutting the leading edge of the sheet to stop it.

The gap between sheets is held to a small and constant lengthby reasonof the fact 'that the fast transport is energized only when the priorsheet has passed the sensing switch location. Even if minor slippageoccurs in the fast transport, this does not unduly increase the gapbetween sheets, since the fast transport is energized untilthe paperreaches the slow transport. A t-the end of the fast transport path, whenthe sheet is decelerated, any large. skew is eliminated by reason of thestopping of the leading edge of the paper so that it lies parallel I tothe path. I

transmitter where sheet scanning occurs.

In this embodiment of the invention, the slow transport comprises a beltwhich is driven slowly and a delivery roller which holds paper againstthe beltfThe sensing switch includes a pair of electrical contactslocated near the nipformed by the belt and delivery roller. Thesecontacts are separated when a sheet of paper is moved to the nip. Whenno paper is present at the nip, the feed roller motor is energized torapidly move a sheet of paper until its leading edge is engaged betweenthe belt and delivery roller. This opens the sensing switch and stopsthe energization of the feed roller. When the slow belt drive has movedthe sheet far enough that its trailing edge passes the switch, theswitch is gain closed to again energize the feed roller motor.

Each new sheet of paper removed from the stack moves rapidly until itsleading edge strikes the nip between the belt and delivery roller. Anylarge skew in the sheet is reduced by reason of the abutting oftheleading edge at opposite sides of its center. If the sheet is skewed,the trailing side of the sheet continues to move forward while theleading side'is stopped, thereby realigning the sheet. l v

The novel features of the invention are set forth with particularity inthe appended claims. The invention will best be understood from thefollowing description when read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 4 is a side elevation view takenon the line'4-4 of FIG.

3; and i FIG. 5 is a diagram of a control circuit used with the a'paratus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a portion ofa facsimile transmitter comprising a frame 11 with a hopper 10 forreceiving a stack of sheets of paper.v Each of the sheets carries animage, which may be a printed or written message, a photograph, or otherinformation. The sheets are fed one at a time along a path past ascanning aperture 12. An electric lamp 14 projects a beam of light thatis reflected and concentrated by a mirror 16 at the scanning aperture. Asystem including a lens 18, mirror 20, and a mechanical light chopper(not shown) scans the image lying within the scanning aperture 12.Electrical circuitry (not shown) converts the dissected opticalimage'into electrical signals for transmission over telephone lines orthe like to a distant receiver, where the image is reconstructed.

In order to transmit the information on the entire stack of sheets inthe hopper 10, the sheets must be moved one at a time along the pathpast the scanning aperture 12. The facsimile transmitter is often usedfor transmission over long distances, such as across the country, andthe charges for use of telephone cables is relatively high. Accordingly,it is desirable to provide as small a gap as possible between thetrailing edge of one sheet and the leading edge of the next, so thattransmission time is not wasted by scanning long gaps. On the otherhand, it is important to make sure that only one sheet at a time ismoved past the scanning aperture, so that all of the information on asheet is transmitted. In addition to providing a small gap betweensheets, the paper feeding apparatus must 7 prevent the introduction oflarge skew. This is because the width of the scanning aperture 12isgenerally adjusted to the width of the paper placed in the hopper 10, toeliminate scanning on either side of the paper. If the paper is skewed,

some portions on either side of the paper will not be scanned,

and the complete imageswill not be transmitted.

The paper feeding mechanism comprises a slow transport means which moveseach sheet of paper slowly past the scanning aperture 12. The slowtransport 22 comprises a rubber belt 24 which extends between a drivewheel 26 and an idler wheel 28. The drive wheel 26 moves at a slowspeed, such as a peripheral speed of one-tenth inch per second, therebymoving the belt past the scanning aperture 12 at the same slow speed. Adelivery roller 30 and pressure roller 32 lie on opposite sides of thebelt, both being idler rollers. The delivery roller 30 has a shaft 34which is fixed in place on the frame 11. The pressure roller 32 isrotatably mounted at the end of an arm 36 that pivots about a point 38,the arm being spring biased upwardly toward the delivery roller. Eachsheet of image-bearing paper is initially received between the deliveryroller 30 and belt 24. The pressure roller 32 deflects downwardlysufficiently to enable receipt of the leading edge of the paper. Thepressure roller then applies the pressure necessary to assure firmengagement of the paper between the delivery roller and belt.

The movement of paper from the hopper to the slow transport 22 isaccomplished by a fast transport means 40 which comprises a pair of feedrollers 42 mounted on a feed roller shaft 44. A reverse roller 46mounted on a reverse roller shaft 48 is disposed on a side of the hopperopposite the feed roller 42. The hopper 10 is tapered to a narrow throatS0, and the feed roller and reverse roller have peripheral portionsextending through openings in the hopper walls immediately above thethroat. A stack 52 of sheets of paper with images thereon to betransmitted is laid in the hopper 10 in an almost vertical position. Abar 53 mounted on the frame lies against the forward face of the stack52 to prevent the paper from falling over. A pair of paper-centeringbrackets 47, which are moved together and apart by a manually turnedlead screw 49, keeps the stack of sheets atthe center of the fasttransport path.

The feed roller shaft 44 is coupled by a chain belt to the output shaft56 of a feed motor 54. initially, the feed motor 54 is energized androtates the feed roller 42 at a rapid rate such as several revolutionsper second. The feed roller engages the sheet shown at 55 at the bottomor back of the stack and moves it downwardly along an initial pathdefined by a guide plate 58. The sheet continues to move along this pathuntil it reaches the forward nip between the delivery roller 30 and thebelt 24. The leading edge of the sheet 55 deflects the belt 24 andpressure roller 32 thereunder downwardly a small amount sufficient forthe leading edge to be engaged between the roller 30 and belt, as shownin FIG. 2.

As the leading edge of the sheet approaches the forward nip at thedelivery roller, it raises a contact 60 of a paper sensing switch 62.The raising of contact 60 breaks an electrical circuit between thecontact 60 and another contact 64 below the paper. The opening of thesensing switch 62 results in the deenergization of the motor 54 and theapplication ofa motor brake (not shown) thereto for a brief time. Thisquickly stops the rotation of the feed roller 42 so that it no longerfeeds paper toward the belt, and the feed roller is then freewheeling.

The sheet 55 is now engaged between the delivery roller 30,

located at the down-path end of the initial path, and the belt 24. Thesheet then moves along another path defined by the belt, toward thescanning aperture 12 at a slow rate, such as one-tenth inch per second.As it passes the scanning aperture, the images thereon are opticallyscanned for transmission. The sheet of paper continues to move along thebelt until it is deposited in an after hopper 66.

When the trailing edge of the sheet passes the paper sensing switch 62,the contact 60 again falls on the other contact 64. This again energizesthe feed motor 54 to drive the feed roller 42, so that the next sheet ofpaper is drawn out of the stack 52 and is moved rapidly along the guideplate 58 to the nip of the delivery roller 30. The inertia of the feedmotor 54 and feed rollers, and their speed ofoperation, is chosen sothat the leading edge of the next sheet reaches the nip ofthe deliveryroller 30 at a time when a trailing edge of the preceding sheet has justpassed the nip. This leaves a gap between sheets, which is chosen to bea small distance such as one-eighth inch. The motor 54 accelerates thefeed roller rapidly, which shakes up" the stack of sheetsin the hopperand jerks the bottom sheet away from the others. It is found that thistends to separate the sheets and substantially reduces the chance thatmore than one sheet will be fed.

The feed rollers 42 are constructed of a soft rubber having a highcoefficient of friction with respect to paper. This coefficient offriction is higher than the coefficient of friction of paper on paper orof the reverse roller 46 on paper. As a result, a sheet of paper incontact with the rotating feed roller 42 is driven along the pathtowards the belt, instead of being held back by another piece ofpaper orby the reverse roller; 46 which is engaged with the other face of thesheet. Some slippage of the feed roller on the paper may occur, but itrarely lasts for more than a fraction of a revolution of the feedroller. Such slippage does not substantially affect the gap betweensuccessive sheets at the scanning aperture 12 because the precedingsheet moves past the scanning aperture only a small fraction of an inchduring even a complete revolution of the feed roller. The advantage ofcontinuous rotation of the feed roller until a sheetis sensed near thenip of the delivery roller can be appreciated by comparison withprevious feed mechanisms wherein the gap between successive sheetsincreased by approximately the total amount of any slippage.

The reverse roller 46 is preferably constructed of a material with alower coefficient of friction on paper than the feed roller 42 on paper,but with a coefficient greater than that between two sheets of paper.The reverse roller may be constructed of a medium-hard rubber or ofrelatively soft plastic. The reverse roller shaft 48 is turned in thedirection indicated by arrow 49 during the entire time that the machineis operating to scan the sheets. As a result, the reverse roller tendsto move any sheet of paper which passes by it, back into the hopper 10.In some instances, two or more sheets may pass between the feed andreverse rollers and through the throat 50 towards the belt. The extrasheets rarely move all the way to the nip, but they may move part of theway. The reverse roller 46 turns slowly, having a peripheral speedapproximately onehalf the belt speed, so that the extra paper isgradually moved back into the hopper. This helps to prevent jamming ofthe feed apparatus. The reverse roller does not move back a sheet whichhas reached the nip of the delivery roller 30, because such a sheet isfirmly engaged between the delivery roller and the belt.

When a sheet from the stack 52 is accelerated by the feed roller towardthe belt, some skew may be imparted. This may occur, for example, if onefeed roller slips while the other does not, or if one feed roller slipsmore than the other, Such skew is generally eliminated when the sheetstrikes the nip of the delivery roller 30. This is because the deliveryroller 30 extends across substantially the entire width of a sheet,except for a center portion of the roller which is of reduced diameter.The reduced diameter portion is provided to accommodate the sensingswitch contact 60 immediately up-path from the nip of the deliveryroller. If a sheet is skewed, its leading edge is not parallel to thelength of the nip of the delivery roller. As a result, one side of theleading edge reaches the nip first, and when it hits the belt ordelivery roller at the nip, the sheet is buckled on the leading side,which causes the reduction of skew.

The facsimile machine is generally left constantly in a standbycondition, so that all of the apparatus is kept heated to operatingtemperature. During standby operation, however, the lamp 14, a copymotor 72 which drives the drive wheel 26, and reverse roller 46 and feedmotor 54 are deenergized. The apparatus may be started by inserting afirst sheet through a manual feed opening 70 to the nip of the deliveryroller 30. The first sheet opens the paper sensing switch 62, whichcauses the apparatus to be placed in an operating state. While themachine is in the operating state, the lamp l4 and copy motor 72 are oncontinuously, while the feed motor 54 is turned on whenever the sensingswitch 62 is closed. The copy motor 72 drives a transmission chain 73that rotates the belt drive wheel 26 and the reverse roller shaft 48.

The first sheet moves along the belt until its trailing edge has passedthe contact 60. At this't'ime, the feed motor 54 rotates the feed roller42 to feed the next sheet to the belt. When a trailing edge of the lastsheet in the stack 52 passes the contact 60, the feed motor 54 is turnedon and the feed roller 42 starts to spin. After a predetermined periodsuch as a few seconds, the machine is placed in a standby, ornonoperating state, wherein the lamp l4 and the motors 54 and 72 aredeenergized. This provides for automatic stopping of the transmissionwhen the last sheet in the stack is transmitted, and also provides forstopping if: amalfunction occurs which prevents feeding to the belt. Inorder to start the machine again, another sheet may be manually fedthrough the slot 70. Alternatively, all of the sheets may be placed inthe stack 52, and a pushbutton depressed for placing the apparatus inthe operating state to start the feeding of the first sheet.

FIG. 5 is a diagram of acircuit which automatically places the paperfeed apparatus in an operating or nonoperating condition, and controlsthe energization of the feed motor. The circuit comprises a pair ofelectrical conductors 80 and 82 for coupling it to a power sourceindicated at 84, which may be an ordinary electrical outlet. A circuitbetween the power source and the copy motor 72 can be completed by anoperating switch 86. The circuit between the feed motor 54 and the powersource can be completed by closing of both the operating switch 86 andthe paper sensing switch 62. A timer 88 monitors the state of the papersensing switch 62 and controls a relay coil 90 which opens and closesthe operating switch 86. If the timer 88 senses that the paper sensingswitch 62 is closed for more than a predetermined period, such asseveral seconds, it operates the coil 90 to open the operating switch86. So long as the sensing switch 62 is opened, or is closed no morethan several seconds, the operating switch 86 remains continuouslyclosed. A pushbutton 92 is provided which is in parallel with theoperating switch 86, to enable bypassing of the operating switch, forinitially turning on the apparatus.

If the paper feed apparatus is in a nonoperating state, it can be placedin an operating state in either of two ways. One way is by manuallyfeeding. a sheet of paper to the nip of the delivery roller, therebyopening the paper sensing switch 62. Upon opening the switch 62, thetimer 88 energizes the coil 90 to close the operating switch 86. Thecopy motor '72 is then energized, so that the belt which moves paperpast the scanning aperture begins to turn. when the trailing edge of thefirst sheet passes by the sensing'switch 62, the sensing switch closesand turns on the feed motor 54. If at least one other sheet is in thestack 52, the sheet will be quickly fed to the belt, and the sensingswitch 62 will again be opened.

Another way of initially placing the apparatus in an operating state isby merely loading a stack of sheets in the hopper and then depressingthe pushbutton switch 92. When the pushbutton is depressed, current canflow to the feed motor 54, enabling the first sheet to be fed to thebelt. The first sheet opens the sensing switch 62,. so that theapparatus can continue to operate. When the trailing edge of the lastsheet has passed the sensing switch 6 2 the switch 62 remains closedwhile the feed motor 54 rotates. After a few seconds,- the timer 88deenergizes the coil 90 to open the operating switch 86. The apparatusis then placed in a nonoperating state.

While the paper feeding apparatus of the invention is useful infacsimile transmitters, itis also useful in a variety of otherapplications. The use of a fast transport to move paper to a mechanismwhich thereafter moves it at a slower speed, and the use of a sheetsensor at the end of the fast transport, assures a small gap betweensheets. The use of means that abut opposite sides-of the sheet tosuddenly slow it, particularly where the sheet is substantially stoppedas where it is slowed to less than an inch per second after traveling atleast several inches per second, enables the substantial reduction ofskew.

Although particular embodiments of the invention have been described andillustrated herein, it is recognized that modifications and variationsmay readily occur to those skilled in the art, and consequently, it isintended that the claims be interpreted to cover such modifications andequivalents.

We claim: 1. Apparatus for feeding individual sheets from a stackcomprising:

fast transport means activatable to move individual sheets from saidstack along a first path at a first speed;

slow transport means disposed to receive individual sheets from saidfirst path, for substantially continually moving I said sheets along asecond path at a second speed which is less than said first speed, saidslow transport means spaced from said fast transport means a distanceless than the length of said sheets;

sheet sensing means for detecting the presence of a sheet at an areanear the intersection of said first and second paths; and

means responsive to said sheet sensing means for terminat ing activationof said fast transport means when said sheet sensing means detects asheet. i l

2. Apparatus for feeding individual sheets from a stack comprising:

fast transport means for moving individual sheets from said stack alonga first path at a first speed of at least several inches per second;

slow transport means disposed to receive individual sheets from saidfirst path, for moving said sheets along a second path at a second speedwhich is less than an inch per second, said slow transport meansincluding means for initially abutting sheets received from said firsttransport means at positions disposed on opposite sides of the center ofsaid first path and disposed along a line substantially perpendicular tosaid paths to reduce large skew; and

sheet sensing means responsive to the presence of a sheet at an areanear the intersection of said first and second paths for deactivatingsaid fast transport means.

3. Apparatus for feeding individual sheets from a stack comprising:

fast transport means for moving individual sheets from said stack alonga first path at a first speed;

slow transport means disposed to receive individual sheets from saidfirst path, for moving said sheets along a second path at a second speedwhichis less than said first speed, said slow transport means includinga delivery roller disposed on one side of said second path and meansdisposed opposite said'delivery roller having a surface for continuallymoving along said second path to carry sheets therealong; and

sheet sensing means responsive to the presence of a sheet at an areanear the intersection of said first and second paths for deactivatingsaid fast transport means, said sheet sensing means including a pair ofcontacts disposed immediately up-path from the nip formed by saiddelivery roller and said means disposed opposite said delivery roller.

4. Apparatus for feeding individual sheets from a stack comprising: r

' fast transport means activatable to move individual sheets from saidstack along a first path at a first speed;

slow transport means .disposed to receive individual sheets from saidfirst path, for moving said sheets along a second path at a second speedwhich is less than said first speed;

sheet sensing means responsive to the presence of a sheet at an areanear the intersection of said first and second path for deactivatingsaid fast transport means; and

means for deactivating said fast transport means after a predeterminedperiod of continual activation greater than the usual time between theactivation of said fast transport means and the arrival of a sheet nearthe intersection of said first and second paths.

5. Apparatus for feeding paper through a facsimile transmittercomprising:

hopper means for holding a plurality of sheets;

means for carrying sheets at a constant slow speed along a scanningpath;

means defining-an initial path between said hopper means and said meansfor carrying sheets at a slow speed;

feed roller means activatable to move individual sheets along saidinitial path at a fast speed which is substantially greater than saidslow speed;

delivery roller means engageable with said means for carrying sheets ata constant slow speed, for holding sheets thereto, said delivery rollermeans disposed at the downpath end of said initial path;

means for sensing the presence of a sheet at a position near saiddelivery roller means; and

means responsive to said means for sensing, for activating said feedroller means until a sheet is sensed.

6. The apparatus defined in claim wherein:

said means for carrying sheets at a slow speed comprises a belt; and

said delivery roller means comprises a roller having portions onopposite sides of the center of said scanning path for engaging saidbelt, and means for biasing said belt and said delivery roller meanstoward each other to abut the leading edge of sheets moved down saidinitial path, whereby to reduce large skew.

7. The apparatus defined in claim 5 wherein:

means for rotating saidfeed roller; and including means for rotatingsaid reverse roller, during periods when said feed roller is stationary,in a direction to move sheets back towards said hopper means, whereby toreturn the second sheet toward the hopper in case of double feeding. 9.Apparatus as defined in claim 5 including: means responsive to saidmeans for sensing, for placing said facsimile transmitter in anonoperating state to cease the transmittal of images, upon the absenceof sensing of a sheet for a predetermined period.

